Abstract: For ENiCrMo-2 nickel-based electrode, 130 mm thick 12Cr2Mo1R high-strength steel was welded by electrode arc welding method, the fracture morphology was observed by tensile test and longitudinal bending test .The hot crack sensitivity of the deposition metal was explored by scanning electron microscope (SEM), the crack sensitivity index of the deposition metal was obtained. The crack resistance of the deposition metal was explained by using the microstructure morphology and grain boundary precipitate, and the fracture morphology of the transverse and longitudinal tensile test of the deposition metal was observed by SEM. The results showed that most of the fractures were tendon fossas, and the size of the tendons was uniform, and no thermal cracks were found in the fractures. The length of cracks on the stretched and longitudinal bending surface of the round rod was calculated by volume microscopy, and the thermal crack sensitivity of the weld metal was calculated to be 2.23 × 10⁻³ and 6.08 × 10⁻³ mm/mm² respectively. JMatPro calculations and microstructure characterization of deposition metals show that the reason for the low crack sensitivity of deposition metals is that the grain boundary morphology is tortuous and there are molybdenum-rich carbides pinning grain boundaries at the grain boundaries.